C Variables

1. What is a Variable?

• A variable is a container (memory location) used to store data values.
• Each variable has:
  • A type → defines the kind of data stored
  • A name → used to identify it
  • A value → the actual data stored in it

👉 Think of a variable as a box that holds a value.

2. Types of Variables in C

3. Declaring (Creating) Variables

To create a variable, we must:

1. Specify the type
2. Give it a name
3. (Optionally) Assign a value

Syntax:

type variableName = value;

Example:

int myNum = 15;

✅ Here:

• int → data type
• myNum → variable name
• 15 → value

4. Declaring Without Assigning

You can declare a variable first and assign a value later.

Example:

int myNum;     // Declaration

myNum = 15;    // Assignment 5. Outputting Variables

Normally, you can print text with:

printf(“Hello World!”);

But to print variable values, C requires format specifiers (like %d, %f, %c).

If you try this:

int myNum = 15;

printf(myNum);  // ❌ Nothing happens

It won’t work because C doesn’t automatically know what type of data you’re printing.

You’ll learn how to print variables in the next chapter using format specifiers.

🧩 Quick Summary